Apparatus for conveying workpieces of paper or plastics material sheeting,preferably for bag-making machines



O United States Patent [1113,543,980

[72] Inventor Friedrich Franz Brockrnuller [56] References Cited A l N gzggg gm m UNITED STATES PATENTS pp o. Filed y 1968 2,l38,406 ll/l938 Huck..... 27l/79X [45] Patented Dec. 1, 1970 Primary Examiner-Edward A. Sroka [73] A i wi d lk & Hokchgr Attorney-Fleit, Gipple & Jacobson Lengerlch, Germany v Pnomy ABSTRACT: The workpieces are fed at a high velocity of [31] M4501 travel and are inserted with their leading end into grippers carried by gripper chains, which revolve at a lower velocity. The spacing of the grippers is smaller than the length of the workpieces. An input feed roll is provided at the charging station [54] APPARATUS FOR CONVEYING WORKPIECES F for the gripper chains and revolves oppositely to the reversing PAPER OR PLASTICS MATERIAL SHEETING, s rockets of the h b0 t h a I PREFERABLY ron BAG-MAKING MACHINES P c am a u 7 Claim 4 D in to the axes of said sprockets and at a peripheral velocity which is higher than the velocity of the grippers. The roll contacts [52] US. Cl. 225/96, the path of the grippers along a generatrix and is provided with 225/ 100; 271/79 peripheral recesses enabling a passage of the grippers [51] Int. 1326f 3/02; therethrough and with vacuum openings on its peripheral sur- B65h 29/28, B65h 10 face between the recesses. The communication between said Field of Search 271/5], vacuum openings and a vacuum conduit is interrupted when the vacuum openings contact the path of the grippers.

Patented 1, 1970 3,543,980

FIG.'3 FIGA INVENTOIv ama/f Rama/valua- HTr RIvEyS APPARATUS FOR CONVEYING WORKPECES OF I PAPER R PLASTICS MATERIAL SHEETWG, PREFERABLY FOR BAG-MAKING MACHHNES This invention relates to an apparatus for conveying workpieces of paper or plastics material sheeting, preferably for bagmaking machines, in which the workpieces are fed at a high velocity of travel and are inserted with their leading end into grippers carried by gripper chains, which revolve at a lower velocity, the spacing of the grippers being smaller than the length of the workpieces.

Apparatus are known in which the gripper chains revolve at the production speed of the preceding production machine and the spacing of the grippers on such chains exceeds the spacing of the workpieces in the production machine by the length of the workpieces in the direction of conveyance. This results in large overall lengths of the apparatus owing to large lengths of the gripper chains. Besides, the high speed of travel of the gripper chains often results in breakdowns and in damage to the workpieces being delivered. In view of the above, it has already been proposed to provide the arrangement described hereinbefore, in which the spacing of the grippers on the gripper chains is much reduced so that the overall length of the apparatus and the speed of revolution are reduced. On the other hand, this arrangement may involve difficulties in the transfer of the workpieces to the gripper chains because the workpieces cover the succeeding gripper of the gripper chains so as to obstruct the proper transfer of the workpieces unless special measures are adopted.

It is an object of the invention reliably to avoid a covering of the grippers by the workpieces in the above-mentioned apparatus for conveying workpieces of paper and plastics material sheeting.

This object is accomplished according to the invention in that an input feed roll is provided at the charging stationfor the gripper chains and revolves oppositely to the reversing tion. When a transverse weakening or transverse cutting device is provided in the production machine consisting, e.g., in a tube making machine, the peripheral velocity of the input roll may even exceed to some extent the velocity of travel in the production machine and the input roll may coact with a second roll so that these two rolls form at the same time the required tear-off rolls.

The input roll may suitably have series of vacuum holes which are disposed between the recesses for the passage of the grippers and which are spaced around the periphery of the input roll and communicate with axial vacuum ducts and the vacuum ducts may open into an end face of the input roll may be covered there by a control ring, which is in sealing contact with the end face and connects the vacuum ducts to the vacuum conduit only in the vacuum zone by means of a recess. It will be particularly desirable if, in a further embodiment of the invention, a controllable shutoff valve is provided in the vacuum conduit close to the input roll and said valve is open only while a workpiece is being fed by the input roll. The controlled shutoff valve prevents an establishment of atmospheric pressure in the entire vacuum conduit leading to the vacuum pump when a workpiece which is fed to the gripper chains is withdrawn form the vacuum rolls but only the short length of the vacuum conduit leading to the shutoff valve so that it will be sufficient to reestablish the vacuum in this short portion of the vacuum conduit during another vacuum operation and a corresponding opening operation of the shutoff valve. The control device for the shutoff valve may comprise a cam which performs one revolution per cycle of the production machine and which is formed by two cam discs that are relatively rotatably mounted on a drive shaft and can be fixed in position and have cam faces forming together the cam. This arrangesprockets of the gripper chains about an axis which is parallel to the axes of said sprockets and at a peripheral velocity which is higher than the velocity of the grippers, the roll contacts the path of the grippers along a generatrix and is provided with a peripheral recesses enabling a passage of the grippers therethrough and with vacuum openings on its peripheral surface between the recesses, and the communication between said vacuum openings and a vacuum conduit is interrupted when the vacuum openings contact the path of the grippers.

The input feed roll sucks the workpieces and positively moves them at high velocity into the range of the grippers, which grip them at the leading edge and advance them at the lower velocity at which the gripper chains revolve. The recesses on the periphery of the vacuum roll enable the passage of the outer gripper parts as the workpieces are being gripped. Because the vacuum is interrupted when the vacuum holes contact the grippers, a perfect transfer to the grippers is facilitated. Owing to the higher velocity of the input feed roll, the trailing portion of the workpiece is advanced in the direction of travel of the gripper chains with formation of a loop while the leading portion of the workpiece is being torn off by the grippers so that said trailing portion cannot cover the subsequent gripper and the latter can properly receive the next workpiece, which is fed by the input feed roll.

in a preferred embodiment of the invention, the point of contact between the input roll and the gripper path may lie adjacent to the lower half of the reversing sprockets, around which the gripper chains move into their lower course. As a result the faster rotation of the input roll causes the trailing portion of the respective workpiece to be moved into the region below the gripper chains and said portion of the workpiece then depends freely under the action of gravity in said region when the workpiece is moved by the grippers into the lower chain course.

It will be particularly suitable if the peripheral velocity of the input roll is equal to the velocity at which the workpieces travel in preceding production machine. In this case, there is no need to connect a retarding device between the production machine and the gripper chains which lead to the delivery stament enables an exact adjustment of the beginning, end, and duration of the action of vacuum at the vacuum roll in dependence on the length of the workpiece.

The invention will be explained more fully in the subsequent specification with reference to the drawing, which shows an embodiment by way of example.

In the drawing,

F [G. 1 is a transverse sectional view showing those parts of a conveying apparatus according to the invention which are required for an understandingof the invention in conjunction with a transverse cutter of a tu'bemaking machine.

FIG. 2 is a fragmentary top plan view showing the apparatus of FIG. 1.

FIG. 3 is a front elevation showing an adjustable cam for controlling the shutoff valve, partly in section, and

FIG. 4 is a side elevation showing-the cam of FIG. 3.

The illustrated apparatus consists essentially of a pair of rolls 1, 2 and an endless gripper chain 3, 3', which has a peripheral velocity that is smaller than the velocity at which the workpieces W are fed by the pair of rolls 1, 2. In the present case, the workpieces W consist of tubes of plastics material sheeting and are used in the manufacture of bags.

The gripper chains consist of two parallel endless chains 3, 3', which revolve in the direction of the arrow a around the reversing sprockets 4, 4. The spacing of the chains 3, 3' is equal to the width of the widest workpieces W which are to be conveyed. Carrying bars 5 are carried between the chains and a plurality of grippers 6 are secured to said carrying bars and extend on a straight line. The carrying bars 5 are secured at their ends to the chains. The pitch t of the gripper assemblies 5, 6 on the gripper chains is smaller than the length of the workpiece W in the direction of travel. The grippers 6 on each carrying a bar are opened and closed in known manner by means of lateral roller levers 7 and stationary cams 8.

The lower roll 2 of the pair of rolls 1, 2 consists of an input vacuum roll and is so arranged adjacent to the lower half of those reversing sprockets 4, 4' around which the gripper chains 3 to 7 move into their lower course that the roll 2 contacts the circular path k on which the grippers move around the reversing sprockets 4, 4. The input feed roll 2 has recesses 9 which are formed in those planes which are at right angles to the roll axis and in which the grippers move. These recesses permit of an opening movement of the grippers. The roll 2 further has series of vacuum holes on its periphery between the recesses. The vacuum holes areradial and communicate with a circular series of axial vacuum ducts 11, which are formed inside the input roll and open at an end face of said roll. The circular series of the openings of the vacuum ducts 11 is covered by a valve ring 12, which is in sealing contact with the end face of the vacuum roll. The valve ring is urged by spring 13 against said end face and is held againstrotation by a locking pin 14. Adjacent to the circular series of the openings of the vacuum ducts 11, the valve ring has an aperture 15, which extends in the range of the angle y from the plane x-x in which the pair of rolls 1, 2 contact and in the direction of travel approximately to the circle k on which the gripper 6 moves. The aperture 15 is connected by the vacuum conduit 16 to the vacuum pump 17. During the rotation of the input roll, the valve ring connects the vacuum conduit 16 only to those vacuum ducts 1 1 which terminate adjacent to the aperture 15 so that only those vacuum bores 10 can exert a vacuum action which are moving through the range of the angle y. Thus, the angle y defines the vacuum zone of the input roll 2. The workpiece is held on the periphery of the input roll 2 by the vacuum action in said vacuum zone.

As the individual workpieces approaching the pair of feed rolls are more or less spaced apart, depending on their length, the vacuum in the input roll and the vacuum conduit is broken as a result of the equalization of pressure with the atmosphere as soon as the trailing end of the workpiece exposes the vacuum openings 10 in the vacuum zone y. This would require a reevacuation of the entire vacuum system by the vacuum pump 17 before the input roll could exert a vacuum action when the next workpiece enters the vacuum zone. In view of the high-production speeds, the new workpiece might be seized by the input roll too late and might not be properly fed to the grippers of the gripper chain. Such an occurrence is prevented by the shutoff valve 18, which is incorporated in the vacuum conduit 16 as closely as possible to the feed roll 2. The shutofi valve is controlled by a cam 19, which performs one revolution per cycle of the production machine. In the embodiment shown by way of example, the cam 19 is secured to the cutter shaft 20 of the transverse cutter 21 in such a manner that the shutoff valve is opened as the leading edge of the workpiece enters thenip of the pair of rolls 1, 2 and the valve is closed as the trailing edge of the workpiece leaves the nip. As a result, the vacuum line conduit remains constantly evacuated from the vacuum pump 17 to the shutoff valve 18 and is sufficient to evacuate the short conduit 16 and those narrow ducts 10, 1 1 of the input roll 2 when the workpiece enters the nip of the pair of rolls 1, 2, which enter the region of the aperture 15 in the valve ring 12. As a result, the time for reestablishing the vacuum in the input roll is substantially reduced. To enable an adaptation of the described control of the shutoff valve 18 to different workpiece lengths, the cam 19 is adjustable as is shown in FIGS. 3 and 4. The cam 19 consists of two individual cam wheels 19, 19, which have the same smaller and larger radii, respectively. The camwheels are relatively adjustable along the arcuate slot 22 to vary the length of the effective cam face in adaptation to workpieces having different lengths. The cam 19 is detachably secured to the cutter shaft by means of the setscrew 23 so that the beginning of the rise and with it the beginning of the opening operation of the shutoff valve 18 can be timed to agree exactly with the arrival of the leading edge of the workpiece at the pair of feed rolls 1 2.

In the present embodiment the pair of rolls 1, 2 serve at the same time as tear-off means, which tears off and singles the tube sections W in known manner from the tubing B, which has been perforated by the transverse cutter 21. For this purpose, the peripheral velocity of the pair of rolls 1, 2 is higher than the velocity at which the tubing travels in the tube making machine. The later velocity is the same as the peripheral velocity of the pair of feed rolls 25.

The gripper chains 3, 3' are positively driven with an adjustable phase relation by gears or chains, not shown on the drawing, from the cutter shaft 20 of the transverse cutter 21. This arrangement ensures that the circle k on which the grippers 6 move will always be reached by the workpiece W at a time where a series of grippers 6 is disposed on said circle.

When the tube section W which have been severed by the transverse cutter 21 from-the tubing B enter the nip of the rolls 1, 2, they are held on the periphery of the input roll 2 by the vacuum action thereof andare positively moved at the high peripheral velocity of said roll along the vacuum zone y into the circle k on which the grippers are moving. The grippers 6 grip the workpieces at their leading end and move them further into the lower course of the gripper chains 3, 3' at the lower peripheral velocity thereof. During this time, the rear part of the tubing is caused by the action of the vacuum zone y to continue its downward movement past the gripper chain at the higher peripheral speed of the vacuum roll and forms the loop shown in FIG. 1. In this operation, the trailing end of the tube section is positively moved out of the range of the next series of grippers 6 in time so that said next series of grippers can grip without obstruction the next tube section fed by the input roll, as is shown in FIG. 1.

A collecting conveyor belt 24, for instance, moves in known manner under the gripper chains 3, 3'. The tube sections are deposited by the grippers 6 on the belt 24 in shingled form.

lclaim:

1. Apparatus for conveying workpieces of paper or plastics material sheeting, preferably for bagmaking machines, in which the workpieces are fed at a high velocity of travel and are inserted with their leading end into grippers carried by gripper chains, which revolve ata lower velocity, the spacing of the grippers being smaller than the length of the workpieces, characterized in that an input feed roll is provided at the charging station for the gripper chains and revolves oppositely to the reversing sprockets (4, 4') of the gripper chains about an axis which is parallel to the axes of said sprockets and at a peripheral velocity which is higher than the velocity of the grippers, the roll contacts the path of the grippers along a generatrix and is provided with peripheral recesses enabling a passage of the grippers therethrough and with vacuum openings on its peripheral surface between the recesses, and the communication between said vacuum openings and a vacuum conduit is interrupted when the vacuum openings contact the path of the grippers.

2 Apparatus according to claim 1, characterized in that the point of contact between the input roll and the gripper path may lie adjacent to the lower half of the reversing sprockets around which the gripper chains move into their lower course.

3. Apparatus according to claim 1 characterized in that the peripheral velocity of the input roll is equal to the velocity at which the workpieces travel in a preceding production machine.

4. Apparatus according to claim 3, characterized in that the production machine comprises a transverse weakening or transverse cutting machine and the peripheral velocity of the input roll exceeds to some extent the velocity of travel in the production machine and the input roll coacts with a second roll to tear off individual tube sections.

5. Apparatus according to any of claims 1, characterized in that the input roll is provided with series of vacuum holes which are disposed between the recesses for the passage of the" grippers and which are spaced around the periphery of the input roll and communicate with axial vacuum ducts and the vacuum ducts open into an end face of the input roll and are covered there by a control ring, which is in sealing contact with the end face and connects the vacuum ducts to the vacuum conduit only in the vacuum zone by means ofa recess.

6. Apparatus according to claim 1, characterized in that a' controllable shutoff valve is provided in the vacuum conduit" close to the input roll and said valve is open only while a work-* piece is being fed by the input roll.

7. Apparatus according to claim 6, characterized in that the control device for the shutofl valve comprises a cam, which is 

